SECTION 6. RESOURCE CORE 2: Muscle Progenitor Cell Core The overall purpose of the Skeletal Muscle Progenitor Cell Core (SMPRC) is to provide a reliable and consistent source of primary skeletal muscle progenitor cells, and their products to enable cutting-edge research related to muscle function and its deterioration during aging. Skeletal muscle precursors are technically demanding to isolate and culture, and a high level of purity and rigorous quality control is essential in generating reproducible data from cells isolated from mice of different ages, particularly as the frequency and function of muscle precursor cells is known to fluctuate with age (reviewed in (1)). Primary skeletal muscle cells are necessary in order to study the effects of host characteristics, including genetic abnormalities, disability, systemic treatments, age, and gender on muscle differentiation and function. The SMPRC Core will directly benefit investigators by providing standardized and validated cells for experimentation, and by reducing the per-experiment cost of cell purification by centralizing reagent and personnel costs. The Specific Aims of the SMPRC are: 1. To implement and maintain a reliable, cost-effective facility for the standardized isolation and culture of mammalian skeletal muscle cells. 2. To provide education and training to Center researchers regarding the optimal use of these cells in aging-related studies. 3. To continually update methods and models in response to researcher needs and new scientific developments. Thus, the Skeletal Muscle Progenitor Cell Core will (1) provide to investigators primary rodent skeletal muscle cells, including both muscle progenitors and differentiated myocytes, as well as the products of these cells (including conditioned medium, protein extracts, RNA, and DMA), (2) consult with and advise investigators in the appropriate design and interpretation of experiments involving muscle precursor cells and muscle differentiation, (3) establish a bank of stored myocyte lines and a database of information regarding these lines that can be provided to investigators as needed, (4) optimize and improve available models and methods to isolate, culture, and differentiate muscle cells to enhance the core's functionality and benefit the research aims of center investigators, and (5) develop and optimize methods for isolation of human skeletal muscle precursors and myocytes, based on protocols currently used to isolate mouse cells and the experience of our faculty (particularly the Core Co-Director, see Budget Justification and attached Biosketch) in isolating related human progenitor cell types.